1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for the gravity toolface of a tool downhole and/or other parameters relating thereto, including inclination, orientation and temperature.
2. Background of the Art
Oil wells (also referred to as wellbores or boreholes) are drilled with a drill string that includes a tubular member (also referred to as a “drilling tubular”) having a drilling assembly (also referred to as “bottomhole assembly” or “BHA”) which includes a drill bit attached to the bottom end thereof. The drill bit is rotated to disintegrate the rock formation to drill the wellbore. The BHA includes devices and sensors for providing information about a variety of parameters relating to the drilling operations (referred to as “drilling parameters”), the behavior of the BHA (referred to as “BHA parameters”) and the formation surrounding the wellbore being drilled (referred to as “formation parameters”). A substantial number of currently drilled wellbores are deviated wellbore and horizontal wellbores. The BHA used for drilling such wellbores usually includes one or more devices configured to steer the BHA so as to drill such wellbores along selected well paths. Such devices include magnetometers to provide measurements of the toolface, which measurements are taken when the BHA is rotating and are also unaffected by the BHA vibration. The magnetometer measurements are typically referenced to the gravity toolface measurements taken by other sensors, such as accelerometers, when the when the BHA is stationary.
The disclosure herein, in one aspect, provides apparatus and methods for determining gravity toolface that may be utilized as a reference for the gravity toolface measurement, which apparatus also may be utilized to determine other measurements, such as inclination, orientation and temperature of the BHA.